Table 1. GIS datalayers used in the decision support system (DSS). Most datalayers were modified slightly from their original source for this analysis. The source column includes an acronym for the agency providing the data and the year of the datalayer used in our analysis. Data processing notes are included in the description column. Full data references are included in the literature cited.

Data Source Source Description Resolution
Soils on U.S. Forest Service land USFS
U.S. Forest Service (Gifford Pinchot National Forest) forest soils and soil map units 1:15,840
Soils on state, county, and private lands NRCS
USDA Natural Resources Conservation Service Soil Survey Geographic Database (SSURGO) for Cowlitz, Clark, and Skamania Counties 1:250,000
Stream hydrography (routed) SSHIAP
Salmon and Steelhead Habitat Inventory and Assessment Program (SSHIAP) unpublished spatial data on hydrology and stream conditions (1:24,000) for Watershed Inventory Area (WRIA) 27 1:24,000
Stream hydrography (drainage enforced and routed) Miller
Routed, cleaned and attributed stream hydrography generated to match SSHIAP hydrography following methods by Miller (2003); Generated to facilitate sediment routing and estimation of channel characteristics 1:24,000
6th Field Hydrologic Unit boundaries (HUCs) BLM
Regional Ecosystem Office (REO) Hydrologic Unit Boundaries for Oregon, Washington, and California, Portland, Oregon, USA 1:24,000
7th Field Hydrologic Unit boundaries (HUCs) Lewis County
Lewis County GIS (2001) data on 7th field hydrologic boundaries for the Lewis watershed unknown
Topography and Geology  
Surficial geology WDNR
Washington State Department of Natural Resources (WDNR) classification of geologic map units according to major lithology (WDNR 2003) 1:100,000
Slope stability WDNR
WDNR predictive data layer of shallow-rapid slope stability from calibrated GIS-based models. Updated for the Lewis watershed using methods by Shaw and Vageois (1999) 1:24,000
Elevation USGS
USGS 10 m drainage enforced Digital Elevation Model (DEM). Multiple DEMs mosaicked, and used to generate hydrographic stream layer, to associate streams with topographic features, and to generate lateral hillslope watersheds for stream segments 1:24,000
Hillslope USGS
Hillslope gradient calculated for every 10-m gridcell in the mosaicked 10-m drainage enforced DEM, using ARC/INFO 1:24,000
SSHIAP barriers WDFW
Salmon and Steelhead Habitat Inventory and Assessment Program (SSHIAP) unpublished data on fish passage barriers (1:24,000) for Watershed Inventory Area (WRIA) 27 1:24,000
Dams BPA
Bonneville Power Administration (BPA) dams and possible hydroelectric development sites (BPA 2001); Original source database converted to a spatial datalayer 1:100,000
Regional ownership ICBEMP
Interior Columbia Basin Ecosystem Management (ICBEMP) regional land ownership 1:100,000
Parcel ownership Clark County
Land ownership, parcel boundaries, and land use for Clark County 1:24,000
Parcel ownership WDNR
Land ownership, parcel boundaries, and land use statistics for Clark, Cowlitz, and Skamania Counties 1:24,000
County ownership CommEn Space Washington Protected Lands Database (PLDB 2004, which includes spatial location and conservation status for private and public lands    -
Urban growth Clark County
Urban growth boundary for Clark County    -
Land use Clark County
Comprehensive plan and land use/zoning for Clark County    -
Land and forest cover IVMP
Interagency Vegetation Mapping Project, Western Cascades (Version 2.0) and Western Lowlands (Version 1.0) Spatial Data 1996 (BLM 2001) 30 m
National Land Cover Data USGS
USGS classification of land cover data from LANDSAT TM satellite imagery (level 2). Generated by USGS using Anderson et al. (1976) protocols. 30 m
Fish Distribution  
Fish distribution WDFW
Washington Department of Fish and Wildlife (WDFW) Salmon and Steelhead Habitat Inventory and Assessment Program (SSHIAP) data on fish distribution for Watershed Inventory Area (WRIA) 27 1:24,000
Roads GP
Forest roads and associated attributes 1:24,000
Roads WDNR
WDNR transportation data layer of roads, railroad, and other land and water transportation routes within Clark, Cowlitz, and Skamania Counties 1:24,000